The present invention generally relates to a tube trimming system for trimming tube ends to the desired length and angle. More specifically, the present invention relates to an automated tube trimming system, including a trim machine and a spherical clamp assembly, useful for weld joints and end fittings.
Conventional tube trimming quality is very dependent on the craftsmanship of the individual. While tube trimming may at first sound like a simple task, due to the combination of base material, wall thickness, large range of diameters, tube ovality and unique part configurations, tube trimming becomes a complex task.
One of the challenges that exist on bent tubes is the problem of bend angle variation. Depending on whether a tube is over or under bent, or bent slightly out of rotation, it will not fit into an assembly fixture with both ends square and true. If the tube is trimmed perpendicular to the tube surface, it will not match up to the mating tube or end fitting correctly. Therefore, the tube must be trimmed with a slight miter to allow the mating tube or end fitting to correctly line up for welding. One of the things that assembly mechanics do to overcome slight variations in bend angles is to slightly miter the end of the tube by hand trimming and grinding. This is a very time consuming process that requires a lot of craftsmanship. Existing tube trimming technology is made to trim the tube square to the tube surface, resulting in a gap when the mating part is assembled.
Conventionally, a tube trimming sequence begins with the tube being located into an assembly fixture. The tube is aligned to the fixture and retained with elastic straps. The tube end is then scribed using a hand held scribing device which is manually rotated along the surface of a scribing header on the fixture. Once a scribe line is made completely around the tube, the tube is removed from the fixture. The assembler then manually trims the tube as close to the scribe line as possible using either a band saw, power shear or hand snips. The tube is then sanded to the scribe line using either a power disc sander or hand held sanding block. The part is then manually deburred and hand cleaned. It is then placed back into the fixture, and the mating part is located to verify the trim operation is acceptable. If the joint is not acceptable, then it is hand worked until a good fit is obtained. This process is all done manually, requiring a high level of skill and craftsmanship to obtain a good fit with the mating part to insure a good weld. The process time for these operations varies greatly depending on the quality of the detail and the skill of the assembly mechanic.
As can be seen from the above conventional process, trimming tubes is a very labor intensive process. In addition to the amount of skill and time required to perform this task, the assembly mechanic is exposed to several sources of cumulative trauma disorder. For example, the repetitive tasks of scribing, cutting, grinding and deburring lead to medical conditions such as carpal tunnel syndrome.
As can be seen, there is a need for an improved tube trimming system for rapidly trimming tubes to an appropriate height and angle. There is a need for such an improved system wherein tubes are trimmed by a robust, reproducible, hands-free method requiring minimal manual labor and minimal factory space.